The invention concerns a measuring instrument for the measuring of properties of a sample which comprises a multitude of particles, such as for example of a plant sample, in particular a cereal sample, wherein the measuring instrument is equipped with a spectroscopy device, with which the spectroscopic properties of the sample can be measured. The invention further concerns a method for measuring properties of a sample which comprises a multitude of particles, wherein a measuring of spectroscopic properties of the sample with a spectroscopy device is provided. Applications of the invention are given in the characterization of particulate samples, in particular in the characterization of plant samples, e.g. of cereal samples.
It is well known to characterize the physical and chemical state of grain through the measuring of spectroscopic properties of the grain. For example, by a spectroscopic measurement the protein content of the grain can be ascertained. The spectroscopic measuring is typically not carried out on individual cereal grain, but on a sample with a multitude of cereal grain. Measuring instruments which are designed for the spectroscopic measuring of grain are for example described in DE 101 197 63 A1 and in DE 103 32 800 A1.
The use of the conventional measuring instruments is limited to the spectroscopic measurement. In practice this may prove disadvantageous, as often further properties, such as for example the specific weight of the cereal grain, have to be ascertained which cannot be derived directly from the spectroscopic properties. Thus further measurements are necessary for which a sample must be transferred from the spectroscopic measuring instrument to another measuring device or, if appropriate, provided in another state of preparation (e.g. larger sample quantities).
The measuring of the specific weight of cereals is for example necessary for the establishment of an insect attack or for an accurate characterization of the moisture contents. With an insect attack the sample contains hollow cereal grain, which is not identifiable with the spectroscopic measuring. For example healthy wheat has a specific weight of 80 kg/hl. A fall below this level may indicate an insect attack.
Hitherto it has been usual in practice to measure the specific weight of grain in that a grain sample is weighed in a measuring tube with a predetermined volume. This method has several disadvantages. Firstly a considerably greater sample volume is needed than this is necessary for spectroscopic measurement. The results are an increased material consumption and a limited comparability of the measurements of the spectroscopic properties and the specific weight. Secondly the conventional method means a high expenditure of time. The slow measurement requiring a careful filling of the grain into the measuring tube is impractical under the conditions of grain technology, for example after the harvest or on a depot. Finally, the conventional technology has a limited reproducibility. The relative weight can only be ascertained with an accuracy of about 10%, which is insufficient for a quantification of a possibly existing insect attack.
There are also measuring instruments known (e.g. U.S. Pat. No. 6,706,989 B2, DE 10 2005 052 769 A1 and DE 43 39 285 A1) for a spectroscopic measurement and a weight measurement for seed, which, however, do not allow a mass density determination on seed.
The disadvantages of conventional measurements on grain mentioned are also given in the measuring of other samples in the form of particles, such as other plant samples or plastic granulates in the plastics industry. For example, it may be necessary for quality monitoring in addition to the chemical composition of plastic particles to ascertain with spectroscopic measurements also physical parameters, such as for example the specific weight.
The objective of the invention is to provide an improved measuring instrument for the characterization of a particulate sample to avoid the disadvantages of the conventional technologies. The measuring instrument must in particular make possible that in addition to the spectroscopic measurement further measurements can be ascertained on the sample with increased accuracy and reproducibility. The objective of the invention is also to provide an improved measuring method to overcome the limitations of the conventional technologies and having a broadened range of application. A further objective of the invention is to indicate applications of the measuring instrument and of the measuring method.
These objectives are solved by a measuring instrument, a grain transporting device and a method of the invention.